During the design of two-axis and three-axis magnetic compass chips, both X-axis and Y-axis magnetic field sensors are required. Sensing units of a magnetoresistive type generally have a single magnetic field sensing direction. For example, consider sensing units that are sensitive to X-direction magnetic fields. In order to detect Y-direction magnetic fields, Y-direction magnetic field sensing units are obtained generally by rotating X-direction magnetic field sensing units by 90 degrees. Next, to improve magnetic field sensitivity of an X- or Y-axis magnetoresistive sensor, a push-pull bridge is generally employed, where a push arm and a pull arm are manufactured discretely, that is, one arm is rotated 180 degrees with respect to the other arm, and then push arm dice and the pull arm dice are connected using wire-bonding.
The Y-axis magnetoresistive sensor described above has the following problems:
1) When X- and Y-axis magnetoresistive sensors are required to be manufactured at the same time in the same plane, because the X- and Y-axis magnetoresistive sensors are discrete devices, integrated manufacturing cannot be realized, thereby increasing the process complexity and affecting measurement accuracy of two-axis or three-axis sensors.
2) A push arm and a pull arm cannot be manufactured using an integrated process, and the discrete chips must be connected with wire-bonds which is a process that also increases the process complexity and affects the measurement accuracy of the sensors.